阅读说明：本技术 一种低熔点聚酯的合成及纺丝制备工艺 (Synthesis and spinning preparation process of low-melting-point polyester ) 是由 张庆喜 詹欣怡 解骢浩 金海霞 裴欢欢 于 2020-06-11 设计创作，主要内容包括：本发明公开了一种低熔点聚酯的合成及纺丝制备工艺,对获取的原材料进行滤渣后,结合催化剂和改性剂加入预热后的反应器皿进行酯化反应；然后对酯化反应产物进行两次缩聚反应,将得到的低熔点聚酯的温度降至常温后取出,并进行切粒,得到多片低熔点聚酯切片,接着对所述低熔点聚酯切片进行多次升温干燥,得到切片原料；最后将所述低熔点聚酯切片原料进行吸湿,并利用两根速度差为1500r/min-2000r/min的高速热辊进行牵引拉伸,经过卷绕得到聚酯长丝,降低成本且降低工艺复杂度。(The invention discloses a synthesis and spinning preparation process of low-melting-point polyester, which comprises the steps of filtering residues of obtained raw materials, adding a catalyst and a modifier into a preheated reaction vessel for esterification reaction; then carrying out polycondensation reaction on the esterification reaction product for two times, cooling the obtained low-melting-point polyester to normal temperature, taking out, carrying out granulation to obtain a plurality of low-melting-point polyester chips, and then heating and drying the low-melting-point polyester chips for multiple times to obtain a chip raw material; and finally, absorbing moisture of the low-melting-point polyester chip raw material, carrying out traction and stretching by using two high-speed hot rollers with the speed difference of 1500-2000 r/min, and winding to obtain the polyester filament, so that the cost is reduced and the process complexity is reduced.)

1. A synthesis and spinning preparation process of low-melting-point polyester is characterized by comprising the following steps:

pretreating the obtained raw materials, and then carrying out esterification reaction;

carrying out polycondensation reaction on the esterification reaction product for two times to obtain low-melting-point polyester chips;

heating and drying the low-melting-point polyester chip for multiple times to obtain a chip raw material;

and carrying out moisture absorption and differential hot rolling on the slice raw material, and winding to obtain the polyester filament.

2. The process for the synthesis and spinning preparation of low melting polyesters according to claim 1, characterized in that said pretreatment of the raw materials obtained is followed by an esterification reaction comprising:

filtering obtained phthalic acid, isophthalic acid, ethylene glycol, diethylene glycol and dodecanediol containing branched chains, preparing into slurry, adding the slurry into a preheated reaction vessel together with a catalyst and a modifier, stirring and mixing, pressurizing and heating under the action of helium until the content of water generated in the reaction vessel is greater than a set value, and finishing the esterification reaction.

3. The process for the synthesis and spinning preparation of low melting point polyester according to claim 2, wherein the esterification reaction product is subjected to twice polycondensation reactions to obtain low melting point polyester chips, comprising:

and carrying out pre-polycondensation on the product obtained after the esterification reaction at a first vacuum pressure and a first reaction temperature, continuously vacuumizing to a second vacuum pressure after a set time, and carrying out polycondensation reaction at a second reaction temperature to obtain the low-melting-point polyester.

4. The process for the synthesis and spinning preparation of low melting point polyester according to claim 3, wherein the esterification reaction product is subjected to twice polycondensation reactions to obtain low melting point polyester chips, further comprising:

and cooling the temperature of the low-melting-point polyester to normal temperature, taking out, and dicing to obtain a plurality of low-melting-point polyester chips.

5. The process for the synthesis and spinning preparation of low melting point polyester according to claim 4, wherein the low melting point polyester chip is dried by heating for a plurality of times to obtain a chip raw material, comprising:

and heating and drying the low-melting-point polyester chip under a third vacuum pressure to obtain chip crystals, and drying the chip crystals at a third reaction temperature for 20-24h to obtain a low-melting-point polyester chip raw material.

6. The process for the synthesis and spinning preparation of low melting point polyesters according to claim 5, characterized in that said chip raw material is subjected to hygroscopic and differential hot rolling and wound to obtain polyester filaments comprising:

and (2) after the low-melting-point polyester chip raw material is sequentially extruded and blown in a side-blown mode, absorbing water vapor in the low-melting-point polyester chip raw material, carrying out traction and stretching by utilizing two high-speed hot rollers with the speed difference of 1500-2000 r/min, and winding to obtain the polyester filament.

Technical Field

The invention relates to the technical field of low-melting-point polyester fibers, in particular to a synthesis and spinning preparation process of low-melting-point polyester.

Background

The low-melting-point fiber and the non-woven fabric can be directly bonded by a hot bonding method, and the method is more environment-friendly and convenient compared with the traditional method for bonding by using a water-based adhesive, so that the method is always an important direction for the development of differentiated products in the chemical fiber industry. The melting point of the PET polyester fiber is about 260 ℃, and the melting point is relatively high, so that the energy consumption in the spinning process is increased, and the technical difficulty in the subsequent processing process is also increased.

The existing methods for preparing low-melting point polyester mainly comprise two methods: (1) the method can effectively reduce the crystallinity and the melting point by adding the third monomer, but in order to achieve the effect, the addition amount of the third monomer is generally higher, so that the spinnability of the polyester melt is poor, and the interference and the influence on the subsequent blending effect of spinning and fibers are easy to cause. Therefore, most low-melting polyesters cannot be used for fiber production (can be used only as raw materials for other polyester products) at present. (2) Another method is monomer replacement, such as PTT polyester obtained by replacing ethylene glycol with 1, 3-Propanediol (PDO) has a melting point of about 225 ℃ and the crystallinity and melting point are reduced by increasing the length of the soft segment. However, PDO has not yet been industrially industrialized on a large scale in China, and the yield at present cannot meet the demand as a monomer. Meanwhile, the above two methods greatly change the chemical composition of PET polyester, which causes an increase in cost or complication of the process.

Disclosure of Invention

The invention aims to provide a synthesis and spinning preparation process of low-melting-point polyester, which reduces the cost and the process complexity.

In order to achieve the purpose, the invention provides a synthesis and spinning preparation process of low-melting-point polyester, which comprises the following steps:

pretreating the obtained raw materials, and then carrying out esterification reaction;

carrying out polycondensation reaction on the esterification reaction product for two times to obtain low-melting-point polyester chips;

heating and drying the low-melting-point polyester chip for multiple times to obtain a chip raw material;

and carrying out moisture absorption and differential hot rolling on the slice raw material, and winding to obtain the polyester filament.

Wherein, after the raw materials are pretreated, the esterification reaction is carried out, which comprises the following steps:

filtering obtained phthalic acid, isophthalic acid, ethylene glycol, diethylene glycol and dodecanediol containing branched chains, preparing into slurry, adding the slurry into a preheated reaction vessel together with a catalyst and a modifier, stirring and mixing, pressurizing and heating under the action of helium until the content of water generated in the reaction vessel is greater than a set value, and finishing the esterification reaction.

Wherein, the esterification reaction product is subjected to twice polycondensation reactions to obtain the low-melting-point polyester chip, and the method comprises the following steps:

and carrying out pre-polycondensation on the product obtained after the esterification reaction at a first vacuum pressure and a first reaction temperature, continuously vacuumizing to a second vacuum pressure after a set time, and carrying out polycondensation reaction at a second reaction temperature to obtain the low-melting-point polyester.

Wherein, carry out twice polycondensation reaction to the esterification reaction product, obtain low melting polyester chip, still include:

and cooling the temperature of the low-melting-point polyester to normal temperature, taking out, and dicing to obtain a plurality of low-melting-point polyester chips.

Wherein, carry on the drying of heating up many times to the said low-melting polyester chip, get the chip raw materials, including:

and heating and drying the low-melting-point polyester chip under a third vacuum pressure to obtain chip crystals, and drying the chip crystals at a third reaction temperature for 20-24h to obtain a low-melting-point polyester chip raw material.

Wherein, the chip raw material is subjected to moisture absorption and differential hot rolling and is wound to obtain the polyester filament yarn, and the method comprises the following steps:

and (2) after the low-melting-point polyester chip raw material is sequentially extruded and blown in a side-blown mode, absorbing water vapor in the low-melting-point polyester chip raw material, carrying out traction and stretching by utilizing two high-speed hot rollers with the speed difference of 1500-2000 r/min, and winding to obtain the polyester filament.

According to the synthesis and spinning preparation process of the low-melting-point polyester, after filter residue is removed from the obtained raw materials, the obtained raw materials are added into a preheated reaction vessel in combination with a catalyst and a modifier to carry out esterification reaction; then carrying out polycondensation reaction on the esterification reaction product for two times, cooling the obtained low-melting-point polyester to normal temperature, taking out, carrying out granulation to obtain a plurality of low-melting-point polyester chips, and then heating and drying the low-melting-point polyester chips for multiple times to obtain a chip raw material; and finally, absorbing moisture of the low-melting-point polyester chip raw material, carrying out traction and stretching by using two high-speed hot rollers with the speed difference of 1500-2000 r/min, and winding to obtain the polyester filament, so that the cost is reduced and the process complexity is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of the steps of a synthesis and spinning preparation process of a low melting point polyester provided by the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

Referring to fig. 1, the present invention provides a synthesis and spinning process for preparing low-melting point polyester, comprising:

s101, pretreating the obtained raw materials, and then carrying out esterification reaction.

Specifically, the obtained phthalic acid, isophthalic acid, ethylene glycol, diethylene glycol and the dodecamethylene glycol containing the branched chain are subjected to filter residue, so that the purity of the obtained raw materials can be ensured, the purity of the low-melting-point polyester prepared later can be ensured, the cost is effectively reduced, and the product quality can be improved; preparing the obtained raw materials into slurry, adding the slurry, a catalyst and a modifier into a preheated reaction vessel together, stirring and mixing, wherein the preheated temperature is generally 80-100 ℃, the reaction efficiency of the esterification reaction can be ensured, and the esterification reaction can be fully performed by stirring for about 30 minutes by using a stirring rod; and then pressurizing to about 0.4MPa under the action of helium, simultaneously heating to about 280 ℃, under the protection of inert gases such as helium, and the like, in the esterification reaction process, generating no other reactant, and effectively ensuring the purity of the prepared product.

S102, carrying out twice polycondensation reactions on the esterification reaction product to obtain the low-melting-point polyester chip.

Specifically, the product obtained after the esterification reaction is subjected to pre-polycondensation at a first vacuum pressure and a first reaction temperature, wherein the pre-polycondensation is performed at a low vacuum stage, the pre-polycondensation is smoothly pumped from normal pressure to an absolute pressure of about 400-; because the temperature of the low-melting-point polyester is higher during production, the low-melting-point polyester is taken out after the temperature of the low-melting-point polyester is reduced to normal temperature, and the low-melting-point polyester is cut into granules by using special equipment to obtain a plurality of low-melting-point polyester chips, so that the subsequent spinning of the low-melting-point polyester is facilitated.

S103, heating and drying the low-melting-point polyester chip for multiple times to obtain a chip raw material.

Specifically, the low-melting-point polyester chip at about 110 ℃ and 130 ℃ is heated to 60 ℃ under a third vacuum pressure with the vacuum degree of-0.1 MPa, and is dried for 4 hours to obtain corresponding chip crystals, the chip crystals are dried for 20-24 hours at a third reaction temperature, namely, at 5-10 ℃ again to obtain a low-melting-point polyester chip raw material with lower water content, and after two continuous heating and drying processes, the water in the low-melting-point polyester chip can be effectively discharged, so that a drier chip raw material can be obtained, the subsequent spinning formation and stretching can be facilitated, and the product quality can be improved. And the process is simple.

S104, carrying out moisture absorption and differential hot rolling on the slice raw material, and winding to obtain the polyester filament.

Specifically, after the low-melting-point polyester chip raw material is sequentially subjected to screw extrusion and cross air blowing, the shape of the chip raw material can be changed, the temperature of the raw material is reduced by utilizing the cross air blowing, the raw material is further dehumidified, the water vapor in the low-melting-point polyester chip raw material is absorbed by utilizing oiling moisture absorption and is sent into a channel, two high-speed hot rollers with the speed difference of 1500r/min-2000r/min are used for traction and drawing, polyester filaments are obtained by winding, the winding speed is 4150-5420m/min and is 50-80m/min, the drawing speed is 1.47-1.71 times between a first hot roller with the speed of 2450-3750m/min and a second hot roller with the speed of 4200-5500m/min, filament fibers are formed, finally, the filament finished products are wound by a winding head, the winding speed is 4150-5420m/min and is 50-80m/min lower than that of the second hot roller, and in the spinning process, the humidity is 50-70%, the low-melting point polyester filament yarn spun by 20-120dtex is obtained, the strength of the finished yarn is more than or equal to 2.8cN/dtex, and the elongation is 40-60%. The purity of the prepared product is effectively guaranteed during esterification reaction and polycondensation reaction, so that additional purification cost and the like are not needed, and finished yarn with high strength and high elongation can be prepared only through conventional esterification reaction, twice polycondensation reaction, heating drying and traction stretching, so that the cost is reduced, and the process complexity is reduced.

According to the synthesis and spinning preparation process of the low-melting-point polyester, after filter residue is removed from the obtained raw materials, the obtained raw materials are added into a preheated reaction vessel in combination with a catalyst and a modifier to carry out esterification reaction; then carrying out polycondensation reaction on the esterification reaction product for two times, cooling the obtained low-melting-point polyester to normal temperature, taking out, carrying out granulation to obtain a plurality of low-melting-point polyester chips, and then heating and drying the low-melting-point polyester chips for multiple times to obtain a chip raw material; and finally, absorbing moisture of the low-melting-point polyester chip raw material, carrying out traction and stretching by using two high-speed hot rollers with the speed difference of 1500-2000 r/min, and winding to obtain the polyester filament, so that the cost is reduced and the process complexity is reduced.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.